The Heavy Laser is a defensive structure which becomes more useful towards the later end of the game. It is an improvement in sheer power over the Light Laser. However, it has less overall power-per-resource and similar things have Rapid Fire against it, making it much less used. Destroyers do not have rapid fire against it and that fact alone may make it better fodder than Light Lasers in certain cases. Although, Destroyers are slow and use a lot of deuterium and so are less likely to be used by certain players. The Light Laser is better in every other way, so it is really up to the player's personal preference.

A battle against Light Fighters will always be won by Heavy Lasers. This will force your opponents to use Bombers, which have much less firepower than Destroyers and are not effective in fleet-against-fleet combat.

The Heavy Laser is a practical, improved version of the Light Laser. Being more balanced than the Light Laser with improved alloy composition, it utilizes stronger, more densely packed beams, and even better onboard targeting systems.

The heavy laser is the logical development of the design of the light laser. The structure is strengthened and improved with new materials. The hulls are significantly more resistant. The energy system and the targeting computer were improved so that the heavy laser concentrates significantly more energy on a target.